The present invention relates generally to exposure, and, more particularly, to an exposure method and apparatus, and a method of manufacturing various devices including semiconductor chips such as ICs and LSIs, display devices such as liquid crystal panels, sensing devices such as magnetic heads, and image pick-up devices such as CCDs, as well as a mask used for micromechanics. Here, the term micromechanics refers to technology for applying the semiconductor IC fabricating technique for fine structure fabrications, thereby creating an enhanced mechanical system that may operate at a level of a micron. The inventive exposure method and apparatus are suitable, for example, for so-called immersion exposure that immerses, in a liquid, a space between a surface of a plate to be exposed and a final surface of a projection optical system, and to expose the plate via the projection optical system and the liquid.
A conventional projection exposure apparatus uses a projection optical system to expose a circuit pattern of a mask (reticle) onto a wafer, etc. A high-resolution exposure apparatus is increasingly demanded. One known solution for the high resolution is to increase a numerical aperture (“NA”) of the projection optical system.
As the increasing NA scheme advances, influence of polarization of light on the imaging performance becomes non-negligible, because the imaging performance becomes different according to polarization directions of the light as an incident angle of the light upon the wafer increases. The influence of the polarization of the light on the imaging performance for the two-beam interference is much greater than that for the three-beam interference. In particular, the recently-proposed immersion exposure problematically has a condition under which no image is formed at all due to the polarization direction of the light.
Therefore, control over the polarization of the exposure light is attempted. See, for example, Proceedings of SPIE, Vol. 5377 (2004), p. 68 (“Reference 1” hereinafter). Reference 1 discusses the polarization control over a line and space (“L/S”) pattern. The polarization control over a contact hole pattern is also studied, because the polarized illumination suitable for the L/S pattern is not always applicable to the contact hole pattern. See, for example, Proceedings of SPIE, Vol. 5040 (2003), p. 1352 (“Reference 2” hereinafter). See also “Intrinsic Problem Affecting Contact Hole Resolution in Hyper NA Era,” 2004 International Microprocesses and Nanotechnology Conference (MNC2004), Oct. 27, 2004, No. 27A-3-2 (“Reference 3” hereinafter).
The s-polarized light or the tangentially polarized light in which an effective light source is polarized in its tangential direction is suitable for a resolution of the L/S pattern, according to Reference 1. On the other hand, for the contact hole pattern, Reference 2 states that the effective polarized light for a dense contact hole pattern is a radially polarized light in which an effective light source is polarized in a radial direction. Reference 3 states, however, that no effective polarized illumination is found at present for the dense contact hole pattern. The contact holes include so-called dense contact holes having crowded contact holes, an isolated contact hole that is an optically isolated or a periodic contact hole, and a semi-dense contact hole that is between the dense contact holes and the isolated contact hole. A contact hole pattern usually includes one or more of the above types.